1. Field of the Invention
This invention concerns a method of operating an air conditioner and, more specifically, it relates to a method of operating an air conditioner particularly upon starting the air conditioner in the winter season or like other cold conditions.
2. Description of the Prior Art
During winter, the temperature inside a chamber, for example, of a coating booth, computer room, clean room and various laboratories to be supplied with conditioned air from an air conditioner is often lowered to about 0.degree.-5.degree. C. before the operation of the air conditioner is started. Accordingly, if the air conditioner is started under such a relatively cold condition to supply a conditioned air at a relatively high temperature as it is into the chamber as described above, the conditioned air is cooled suddenly when brought into contact with the surfaces of inner walls of the chamber and equipment installed therein. In this case, a so-called dewing phenomenon occurs, in which the moisture contained in the air cause condensation to form water droplets on the surfaces of the inner walls or the equipments.
FIG. 1 is a diagram for illustrating the generation of the dewing phenomenon, in which a dry-bulb temperature (.degree.C.) is indicated on the abscissa and the absolute humidity (g/kg') is indicated on the ordinate.
It is assumed here, for example, that an air controlled to a humidity at 80% (refer to curve (I)) which is ideal for a coating booth or the like is supplied at a temperature of 20.degree. C. (point A). Then, the dew point for the air is determined as a crossing point B at about 16.degree. C. between the horizontal extension from the condition point A and the saturation curve (II). Accordingly, if the temperature at the inner wall of the coating booth or the equipments such as a coating machine or a reciprocator installed therein is lower than 16.degree. C., that is, the temperature at the point B, the dewing phenomenon is resulted to form water droplets on the surfaces thereof.
Accordingly, during winter where the temperature in the coating booth is usually lowered to about 0.degree.-5.degree. C., if air conditioned by the air conditioner to a relative humidity of about 80% by humidifying the atmospheric air is supplied, it frequently causes the dewing phenomenon.
Even in a case where the atmospheric air, for example, at about 40% relative humidity is supplied to the coating booth while being conditioned only for the temperature under heating to 20.degree. C. (that is, with no humidification) by using an air conditioner equipped only with a temperature controller, the dew point for the supplied air lies at the temperature on the point E where the horizontal extension from the condition point D for the air intersects the saturation curve, that is, at about 5.degree. C. Also during winter dewing phenomenon tends to occur in the winter season where the temperature inside of the coating booth is usually lowered about to 0.degree.-5.degree. C.
If water droplets are once formed to the surfaces of the inner walls or the coating machines or the likes in the coating booth, dust tends to adhere and contaminate the surfaces and droplets would fall to deposit on the coated films upon working the coating equipments thereby resulting in defective coating. In addition, when the droplets thus formed are evaporated, the humidity in the chamber rises abruptly failing to attain moderate control by the air conditioner for the temperature and the humidity in the chamber.
Accordingly, upon starting the coating operation in the coating booth, it is required to heat the inside of the chamber for a time until a desired temperature is reached and a time for heating to completely evaporate the water droplets deposited to form to the inner wall of the booth or the equipments installed therein is also required. Thus, the method for starting the air conditioner involves an inconvenience that the air conditioner has to be operated preliminarily for one hour or so before starting the operation of the coating booth.
Furthermore, if water droplets are formed on the surfaces of the coating equipments installed in the coating booth as described above or the surfaces of various electronic equipments installed within a computer chamber, rust or electric troubles may resulted to this equipment.
Particularly, in the case of supplying an air at a relatively high temperature and a high relative humidity controlled by an air conditioner equipped with a temperature controller and a humidity controller to the inside of the chamber, the dewing phenomenon occurs most frequency always as described above thereby remarkably causing troubles such as rusting or electrical failures to the equipments.